The only thing i can suggest is to reinstall the program, open it hit the restore xp logon screen button.Then you can uninstall and it should be back to normal.Good Luck
I recently installed the program LogonStudio, I quickly realized I didn't like it. SO i uninstalled it however it still changed my logon/logoff screen. I then proceded to search through my computer (using search and manually with explorer) and delete any traces of the program i could find. After that I proceded to go into the registry (using run "regedit") and delete any mention of the program in my registry that i could find, however the program still is controlling my logon screen. I would really appreciate any help on how to finish off this program. I am running Windows XP SP2, if you need anything else just ask... Thanks for any help!
-Justin

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic